Track shunting apparatus



p 1937. G. w. BAUGHMAN 2,092,824

TRACK SHUNTING APPARATUS Filed Dec. 23, 1932 INVENTOR GeorgeWfBaug/mzazz HIS ATTORNEY Patented Sept. 14, 1937 TRACK SHUNTINGAPPARATUS George W. Baughman, Pitt'sburgh,'Pa., assignor to The UnionSwitch & Signal Company, Swissvale, Pa., a corporation of PennsylvaniaApplication December 23, 1932, Serial No, 648,609

11 Claims." (01. 24634) 7 Q My invention relates to track shuntingapparatus, and more specifically to apparatus'for,

shunting track circuits by light weight rail vehicles having steelwheels or pneumatic tired wheels.

I will describe one form of track shunting apparatus embodying myinvention, and will then point out the novel features thereof in claims.

The track shunting apparatus set forth in my present application issomewhat similar to that set forth in the copending application ofHoward A. Thompson, Serial No. 629,030, filed on August 16, 1932, forApparatus for decreasing rail contactresistance, and also the copendingapplicafiled on November .25, 1932, for Track shunting apparatus, whichcopending applications contain claims covering broadly certain featuresof the invention described in my present application.

no The accompanying drawing is a diagrammatic View showing one form, ofapparatus embodying my invention, as applied to an alternating currenttrack circuit.

It has been found that by impressing a voltage to cause an appreciablecurrent to flow between a rail contact and the rail surface, theresistance film which is ordinarily present on the rail surface can beeffectively broken down, and the volt.-

age-impressing circuit, or portions thereof, may

be so arranged as to become available as shunt paths from rail to rail,for the fiow of track circuit current, to cause shunting of the trackrelay, thereby providing the necessary protection to following traffic.In practice, however, the impedance of the voltage-impressing circuit isusually appreciable, thereby reducing the effectiveness of the shuntpaths from rail to rail, particularly in the case of alternating currenttrack circuits.

One object of my invention is to providea low impedance track shuntingpath, at the same time providing an effective rail film breakdowncircuit, Other objects and advantages will be apparent from thedescription which follows.

Referring to the drawing, the track section D-E is providedlwith theusual type of alternate ing current track circuit comprising a trackrelay TR, and a track transformer T energized from a wayside source BXCXand supplying alternating track circuit current to the. rails of thetrack through a limiting reactor X. The re-. maining apparatusillustrated is intended to be carried on the rail vehicle,

The alternating current generator G is driven by a motor M, energizedfrom the car battery CB,

and supplies the rail film breakdown energy tion of Bernard E. OHagen,Serial No. 644,180,

through the medium of two transformersshown within the'dottedrectangles'T andfI' which, if desired, may have a common core, theenergy of transformer T being applied to rail 5 by con-,-. tact shoesl2, and the energy of transformer 'I being applied to rail fi'bycontact'shoe st3 4. Transformer T has a primary winding 1 shown in twosections for purposes of illustration, and a secondary made up of twowindings 8 and 9 having substantially the same number of turns. 10: Theplus terminal of winding 8 is connected to the rail shoe 1, and theminusv terminal of winding 9 is connected to the rail shoe 2 through theprimary winding E5 of a current transformer T the pur-. pose of whichwill be explained hereinafter. 7 The 15 two remaining terminals ofwindings} and 9 are connected together througha reactor X 7 TransformersT and T and reactors X and X are preferably similar in design, and the0011-, nections of windings l0 and H of transformer 20 T are made in ananalogous manner to that de-. scribed for transformer T 'Ihemid-pointsof reactors X and X are joined together by a'low resistance conductorll'which is firmly fastened to therespective reactors to minimize thedanger 5 of breakage, ,asthe shunting effectiveness of the apparatusisin a-large measure dependent upon the integrity of conductor l2. 1 7

It will be apparent from the drawing that the voltage which causesthe-film breakdown current 30 to flow between rail shoes I and .2 andthe rail, is the sum of the voltages induced in windings 8 and 9.Similarly, the film breakdown current through rail shoes 3 and 4 iscaused by the added voltages of windings H! and H. When the wind- 35ings oftransformers T and T are independent I magnetically, thebreakdown current in rail 5 is practically independent of the breakdowncurrent in rail 6, making itpossible for any one rail shoe of the groupto make imperfect contact with the 9,0 rail without materially affectingthe value of the breakdown current in the other rail or the magnitude ofthe'breakdown voltag'e'effective at the rail with which imperfectcontact is being made. However, based on other considerations to be ex-5L5 plained hereinafter, it may be desirable to'use a common core fortransformers T andT?,-hav,-' ing asingle primary winding and. foursecondary windings mounted thereon. v

When 'the film breakdown currents in rails 5 59 and 6 are ,of sufficientmagnitude, indicating that the rail contact resistance at shoes l.2 and34 has. been reduced to a satisfactorily low value, sufficient voltagewill be induced in the secondary windings l3 and I4 of currenttransformers T. 5?

and T to pick up relays K and K through their respective rectifiers Rand R thereby closing the energizing circuit for indicator L over frontcontacts I! and I8, to provide a visual indication to the car operatorthat the apparatus is functioning properly. Primary windings I5 and I6of transformers T and T can also be connected in series with the primarywindings I and I1 respectively of transformers T and T to eliminate theimpedance of windings I5 and I6 from the film breakdown current path,and also from the track shunting path which includes rail shoes 2 and 4.However, by connecting windings I5 and I6 as illustrated, a check isprovided on short circuits occurring in windings 8-9, and IDI I, whichmight otherwise remain undetected. The impedance of windings I5 and I6is sufiiciently low to cause no serious interference with the properoperation of the apparatus.

When the rail film has been broken down at the rail shoes I2 and 34,there will exist two shunt paths from rail 5 to rail 6, one of whichincludes rail shoe I, winding 8, one-half of reactor X conductor I2,one-half of reactor X winding I0, and rail shoe 3, and the other ofwhich includes rail shoe 2, windings I5 and 9, the other half of reactorX conductor I2, the other half of reactor X windings II and I6, and railshoe 4. Assuming that substantially equal track shunting currents fromthe track circuit source BX-CX flow over each of the two shunt paths,the directions which these currents take through windings III and I I,and the two halves of reactor X will be opposing, thereby substantiallyneutralizing the reactance of windings I0 and II and of reactor X withrespect to the track circuit current. In a similar manner, the reactanceof windings 8 and 9, and of reactor X will be substantially neutralized,so that the shunt path between rail shoes I and 3 will consist chieflyof the resistance of the windings and connections in this path.Similarly, the shunt path between rail shoes 2 and 4 will be mainly aresistance path, plus the comparatively small impedance of windings I5and I6. If the impedance of a winding such as I5 is objectionable, asecond winding on transformer T similar to winding I5, can be used, thiswinding being connected between winding 8 and rail shoe I in suchdirection that the currents in the two shunt paths will oppose eachother in these windings, to neutralize the reactance.

By using heavy copper in the secondary windings of transformers T and Tin reactors X and X as Well as in windings I5 and I6 of transformers Tand T the shunt resistance can be made sufliciently low to providereliable and safe shunting of the track relay TR. Should one or morerail shoes fail to make satisfactory contact with the rail, one or bothrelays K and K will release, deenergizing indicator L to warn theoperator immediately of the unsafe shunting condition. Reactors X and Xserve to limit the magnitude of the film breakdown current, to conservethe output of generator G. If desired, a set of the shunting apparatuscan be installed at both ends of the car, to provide shunting protectionwhen the car is bridging insulated rail joints.

It will be apparent that the shunting apparatus disclosed may also beused on direct current track circuits. In the case of alternatingcurrent track circuits, the frequency of the current supplied bygenerator G should be sufiiciently different from the track circuitfrequency to avoid the possibility of false operation of the trackrelay.

To decrease the impedance of the two shunt paths from rail to rail,particularly if the currents in the two paths are not equally divided,reactors X and X may be eliminated from the shunt paths and connected inseries with primary windings I and II respectively, if two separatecores are used for transformers T and T or, if a common core is used, asingle reactor in series with the common primarywinding may be used forlimiting the maximum film breakdown current. In the latter case,however, the breakdown voltage in one rail path will not be completelyindependent of the breakdown voltage in the other rail path. With thereactors X and X eliminated from the secondary circuits of transformersT and T windings 8 and 9, and II and I I, may be replaced by singlesecondary windings having their mid-points joined together by conductorI2.

If it is desired to prevent the feed-over of track circuit currentaround insulated rail joints which will, at times,'be located betweenthe shoes I2 and 34, the common core transformer in which the windings8, I I], 9 and II are linked magnetically, can be used advantageously.By choosing the relative direction of windings 8-Iil and 9--II in suchmanner that the fluxes set up by track circuit current from rail to railtend to neutralize each other, substantially zero potential with respectto the track circuit source will exist between the rails beyond theinsulated joints, thereby preventing possible false energization of atrack relay in an adjoining track circuit.

Although I have herein shown and described only one form of trackcircuit shunting apparatus embodying my invention, it is understood thatvarious changes and modifications may be made therein within the scopeof the appended claims without departing from the spirit and scope of myinvention.

Having thus described my invention, what I claim is:

1. In combination with a rail vehicle and a stretch of railway track, asource of varying current on said vehicle; two transformers on saidvehicle, one for each rail of the track, each having a primary windingenergized from said source, and a secondary winding, the voltage of eachsecondary winding being applied across a portion of the rail associatedtherewith by means of rail contacts to break down the rail film betweensaid rail contacts and the rail; and a connection from the mid-point ofone secondary winding to the mid-point of the other secondary windingfor completing a shunt path from one to the other rail for shunting saidtrack.

2. In combination with a rail vehicle and a stretch of railway track, asource of varying current on said vehicle; a transformer on, saidvehicle having a primary winding energized from said source and havingtwo secondary windings, one for each rail, the Voltage of each secondarywinding being applied across a portion of the rail associated therewithby means of rail contacts to break down the rail film between said railcontacts and the rail; and a connection from the mid-point of onesecondary winding to the midpoint of the other secondary winding forcompleting a shunt path from one tothe other rail for shunting saidtrack. 7

3. In combination with a rail vehicle and a stretch of railway track, asource of varying current on said vehicle; a transformer having aprimary winding energized from said source and having two secondarywindings, one for each rail, each secondary winding comprising twosubstantially equal sections joined together through a reactor whichconnects terminals of opposite polarity of the two sections, the voltageof each of said two secondary windings being applied across a portion ofthe rail associated therewith by means of rail contacts to break downthe rail film between said rail contacts and the rail; and a connectionfrom the mid-point of one reactor to the mid-point of the other reactorfor completing a shunt path from one to the other rail for shunting saidtrack.

4. In combination with a rail vehicle and a stretch of railway track, asource of varying current on said vehicle; a transformer on said vehiclehaving a primary winding energized from said source and having twosecondary windings, one for each rail, the voltage of each secondarywinding being applied across a portion of the rail associated therewithby means of rail contacts to break down the rail film between said railcontacts and the rail; an indicator for each rail controlled by the filmbreakdown current flowing between a rail and its associated railcontacts for indicating that the rail film has been broken down, and aconnection from the midpoint of one secondary winding to the mid-pointof the other secondary winding for completing a shunt path from one tothe other rail for shunting said track.

5. In combination with an alternating current track circuit, a source ofvarying current of such character as to be incapable of operating saidtrack circuit; two transformers, one for each rail of the track, eachhaving a. primary winding energized from said source and each having asecondary winding the terminals of which are connected across a portionof the rail associated therewith by means of rail contacts for breakingdown the rail film between said rail contacts and the rail; and aconnection from the mid-point of one secondary winding to the mid-pointof the other secondary winding for completing a shunt path from one tothe other rail for shunting said track circuit.

6. In combination with an alternating current track circuit, a source ofvarying current of such character as to be incapable of operating saidtrack circuit; a transformer having aprimary winding energized from saidsource and having two secondary windings, one for each rail, the voltageof each secondary winding being applied across a portion of the railassociated therewith by means of rail contacts to break down the railfilm between said rail contacts and the rail; and a connection from oneto the other secondary winding for completing a shunt path from one tothe other rail for shunting said track circuit, said connection beingmade at such point of each of said two secondary windings that trackcircuit currents fiowing from rail to rail over said shunt path willresult in substantially equal and opposite flux linkages in each of thetwo' secondary windings thereby decreasing the impedance of said shuntpath to improve shunting of said track circuit.

'7. In combination with an alternating current track circuit and a railvehicle, a source of varying current on said vehicle of such characteras to be incapable of operating said track circuit; a transformer onsaid vehicle having a primary winding energized from said source andhaving two secondary windings, one for each rail, of

substantially equal flux linkages, the voltage of each of said twosecondary windings being applied across a lengthwise portion of the railassociated therewith by means of a forward and a rear rail contact tobreak down the rail film between said contacts and the rail, therelative directions of said two secondary windings being such that thefluxes caused by the rail to rail track circuit current aresubstantially neutralized therein; and a connection from the midpoint ofone secondary winding to the mid-point of the other secondary Windingfor completing a shunt path from rail to rail to shunt said trackcircuit, said path being also eifective atsuch times as said forward andrear rail contacts bridge insulated rail joints for preventing feedo-verof track circuit current beyond the rail joints due to said neutralizingaction of the secondary windings.

8. In combination with .a railway vehicle operable along metallic rails,a plurality of shunt shoes on the vehicle in contact with each of therails, a source of alternating current energy on the vehicle, atransformer having a first secondary winding inducing said alternatingcurrent in a circuit including two of the shunt shoes contacting withone rail, a second secondary winding of the transformer inducing saidalternating current in a. circuit including two of the shunt shoescontacting with the other cuit including the other of said secondarywindings and two of the shunt shoes contacting with the other rail.

10. In combination with a railway vehicle operable along metallic rails,a plurality of shunt shoes on the vehicle in contact with each of the rrails, a source of alternating current on the vehicle, a transformerhaving a primary winding rail, a first relay energized in accordancewith" the amount of current flowing in the first secenergized from saidsource and having two secondary windings, a first circuit including oneof said secondary windings and two of the shunt shoes contacting withone rail, a second circuit including the other of said secondarywindings and two of the shunt shoes contacting with the other rail,and'a shunting connection from said first to said second circuit.

11. In combination with a track circuit, a source of current of suchcharacter as to be incapable of operating said track circuit; atransformer having a primary winding energized from said source andhaving two secondary windings, one for each rail, the voltage of eachsecondary :winding being appliedacross a portion of the rail associatedtherewith by means of rail contacts to break down the rail film betweensaid rail contacts and the rail; and a connection from one to the othersecondary winding for completing a shunt path from one to the other railfor shunting said track circuit.

GEORGE W. BAUGHMAN.

